Source material delivery system, euv radiation system, lithographic apparatus, and methods thereof

Abstract

A method includes ejecting initial droplets of a material using a nozzle. The method includes applying a pressure on the nozzle using an electromechanical element. The method includes controlling the applied pressure on the nozzle using an electrical signal generated by a waveform generator. The electrical signal includes a first periodic waveform and a second periodic waveform. The method includes coalescing the initial droplets to generate coalesced droplets based on the first and second periodic waveforms and drag. The method includes generating a detection signal, using a detector, corresponding to time intervals between crossings of coalesced droplets at the detector. The method includes determining at least first and second ones of the time intervals using a processor.

1 . A system comprising:
 a nozzle configured to eject initial droplets of a material through a gas;   an electromechanical element disposed on the nozzle and configured to apply a pressure on the nozzle; and   a waveform generator electrically coupled to the electromechanical element and configured to generate an electrical signal to control the applied pressure on the nozzle, wherein the electrical signal comprises a first periodic waveform having a first frequency and a second periodic waveform having a second frequency different from the first frequency and a ratio of the second frequency to the first frequency is between approximately 20-150, and   wherein the system is configured to generate coalesced droplets from a coalescing of the initial droplets based on the first and second periodic waveforms and drag.   
     
     
         2 - 4 . (canceled) 
     
     
         5 . The system according to  claim 1 , wherein the second periodic waveform comprises a square wave. 
     
     
         6 . The system according to  claim 1 , wherein the second frequency is an integer multiple of the first frequency. 
     
     
         7 . The system according to  claim 1 , wherein the first and second periodic waveforms are in superposition. 
     
     
         8 . The system according to  claim 1 , wherein a velocity distribution of the initial droplets are based on perturbations from the applied pressure in response to the first and second periodic waveforms. 
     
     
         9 . The system according to  claim 1 , wherein each of the coalesced droplets has a similar velocity and gap therebetween. 
     
     
         10 . The system according to  claim 1 , wherein:
 a maximum distance, measured from the nozzle, at which the coalesced droplets form without remnant uncoalesced droplets defines a maximum coalescence length of the system, and   the system is configured to adjust the maximum coalescence length by adjusting at least the ratio of the second frequency to the first frequency.   
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . The system according to  claim 1 , wherein:
 a maximum distance, measured from the nozzle, at which the coalesced droplets form without remnant uncoalesced droplets defines a maximum coalescence length of the system, and   the system is configured to adjust the maximum coalescence length by adjusting at least a density or temperature of the gas.   
     
     
         14 . The system according to  claim 1 , wherein:
 a distance, measured from the nozzle, at which the coalesced droplets form without remnant uncoalesced droplets defines a coalescence length of the system, and   the system is configured to adjust the coalescence length by adjusting at least a relative phase between the first and second periodic waveforms.   
     
     
         15 - 18 . (canceled) 
     
     
         19 . A method comprising:
 ejecting initial droplets of a material using a nozzle;   applying a pressure on the nozzle using an electromechanical element;   dispensing gas in the path of the material;   controlling the applied pressure on the nozzle using an electrical signal, generated by a waveform generator, comprising a first periodic waveform having a first frequency and a second periodic waveform having a second frequency different from the first frequency and a ratio of the second frequency to the first frequency is between approximately 20-150; and   coalescing the initial droplets to generate coalesced droplets based on the first and second periodic waveforms and drag.   
     
     
         20 . A method comprising:
 ejecting initial droplets of a material using a nozzle;   applying a pressure on the nozzle using an electromechanical element;   controlling the applied pressure on the nozzle using an electrical signal generated by a waveform generator, wherein the electrical signal comprises a first periodic waveform and a second periodic waveform;   coalescing the initial droplets to generate coalesced droplets based on the first and second periodic waveforms and drag;   generating a detection signal, using a detector, corresponding to time intervals between crossings of coalesced droplets at the detector; and   determining at least first and second ones of the time intervals using a processor.   
     
     
         21 . The method of  claim 20 , wherein the determining further comprises determining an uncertainty of the time intervals based on the at least first and second ones of the time intervals. 
     
     
         22 . The method of  claim 21 , further comprising determining an occurrence of a jump boundary based on at least the uncertainty of the time intervals using the processor. 
     
     
         23 . The method of  claim 22 , wherein the controlling comprises adjusting a parameter of the electrical signal based on the occurrence of the jump boundary. 
     
     
         24 - 26 . (canceled) 
     
     
         27 . A non-transitory computer readable medium having instructions stored thereon, that, when executed on a processor, cause the processor to perform operations, the operations comprising:
 receiving a detection signal from a detector of a source material delivery system, wherein the detection signal is associated with time intervals between crossings of coalesced droplets at the detector; and   determining at least first and second ones of the time intervals based on the detection signal.   
     
     
         28 . (canceled) 
     
     
         29 . The non-transitory computer readable medium of  claim 27 , wherein the determining further comprises determining an uncertainty of the time intervals based on the at least first and second ones of the time intervals, and the operations further comprise determining an occurrence of a jump boundary based on at least the uncertainty of the time intervals using the processor. 
     
     
         30 . The non-transitory computer readable medium of  claim 29 , wherein:
 the operations further comprising controlling an applied pressure on a nozzle of the source material delivery system using an electrical signal generated by a waveform generator;   the electrical signal comprises a first periodic waveform and a second periodic waveform; and   the controlling comprises adjusting a parameter of the electrical signal based on the occurrence of the jump boundary.   
     
     
         31 - 33 . (canceled) 
     
     
         34 . A system comprising:
 a nozzle configured to eject initial droplets of a material;   an electromechanical element disposed on the nozzle and configured to apply a pressure on the nozzle;   a waveform generator electrically coupled to the electromechanical element, wherein
 the waveform generator is configured to generate an electrical signal to control the applied pressure on the nozzle, 
 the electrical signal comprises a first periodic waveform and a second periodic waveform, and 
 the system is configured to generate coalesced droplets from a coalescing of the initial droplets based on the first and second periodic waveforms; 
   a detector configured to generate a detection signal comprising information of time intervals between crossings of the coalesced droplets at the detector; and   a processor configured to determine at least first and second ones of the time intervals.   
     
     
         35 . The system of  claim 34 , wherein the determining further comprises determining an uncertainty of the time intervals based on the at least first and second ones of the time intervals. 
     
     
         36 . The system of  claim 35 , wherein the processor is further configured to determine an occurrence of a jump boundary based on at least the uncertainty of the time intervals. 
     
     
         37 - 39 . (canceled)